Field of the Invention
The embodiments of the invention relate to an organic light emitting display and a driving method thereof.
Discussion of the Related Art
An active-matrix organic light emitting display comprises organic light emitting diodes OLEDs that emit light themselves, and has the advantages of fast response time, high luminous efficiency, high luminance, and wide viewing angle.
An OLED, which is a self-luminous device, comprises an anode and a cathode, and organic compound layers formed between the anode and cathode. The organic compound layers comprise a hole injection layer HIL, a hole transport layer HTL, an emission layer EML, an electron transport layer ETL, and an electron injection layer EIL. When an operating voltage is applied to the anode and the cathode, a hole passing through the hole transport layer HTL and an electron passing through the electron transport layer ETL move to the emission layer EML, forming an exciton. As a result, the emission layer EML generates visible light.
In an organic light emitting diode display, pixels each comprising an organic light emitting diode are arranged in a matrix, and the luminance of the pixels is adjusted based on the grayscale of video data. Each individual pixel comprises a driving TFT (thin-film transistor) that controls the drive current flowing through the OLED based on a voltage Vg applied between its gate and source electrodes, and adjusts the display's grayscale (luminance) by the amount of light emitted by the OLED, which is proportional to the drive current.
Each pixel is connected to a source driver via a data line and to a scan driver via a scan line. Each pixel may be further connected to an emission driver via an emission line.
For use on such organic light emitting displays, the technology for adjusting an emission duty of OLED using the emission driver was developed, in order to reduce display defects (known as “mura”) that are produced in the laser annealing process of a TFT process. However, this leads to the problem of increased power consumption.